A cathode ray tube (CRT) is a video display component of many televisions and computer monitors. A typical CRT weighs between 15 and 90 pounds and contains significant quantities of lead, barium, and other elements that are added to the specialized CRT glass, in some cases to protect the user from x-rays generated within the operating CRT. CRT glass is comprised of up to 25% lead oxide (PbO). The major hazardous components of CRTs are lead and barium found in the glass and seal components. The lead content of a typical color CRT is about 2.5 lb. Most of the lead is found in the funnel glass and the face plate-funnel seal since most manufacturers have eliminated lead from the panel glass and the neck glass represents a relatively small part of a typical tube. The glass for the funnel and neck sections are characterized by high levels of lead oxide and the glass for display panel typically contains high levels of barium oxide [2-4].
A major obstacle to reuse and disposal is the fact that the leachability of lead causes the CRT components to fail the EPA TCLP leaching test [5]. Because of the high lead content, CRT glass is no longer to be disposed of in the trash or in municipal landfills. While CRT glass may be disposed of in hazardous waste landfills, this is a costly option and recycling is the preferred management option for end-of-life CRTs. Currently, CRTs are recycled through a process which involves extracting the lead using a smelting process. The smelting process is costly and results in high levels of air and water pollution. Cathode ray tubes presently have a negative value due to the difficulty and hazards associated with recycling and/or disposing of them. Similar difficulties in disposal arise with other glasses containing hazardous materials, such as fluorescent light bulbs.
Methods have been developed for converting waste glass into ceramic products. However, established methods for conversion of waste glass into other useful materials (e.g., ceramics) do not address the hazardous components of CRT glass and other hazardous waste glasses. The field currently lacks suitable techniques for the safe encapsulation of heavy metals and other hazardous compounds into products and/or materials made from CRT glass and other hazardous waste glass.